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author | lloyd <[email protected]> | 2014-01-10 03:41:59 +0000 |
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committer | lloyd <[email protected]> | 2014-01-10 03:41:59 +0000 |
commit | 6894dca64c04936d07048c0e8cbf7e25858548c3 (patch) | |
tree | 5d572bfde9fe667dab14e3f04b5285a85d8acd95 /src/lib/entropy/entropy_src.h | |
parent | 9efa3be92442afb3d0b69890a36c7f122df18eda (diff) |
Move lib into src
Diffstat (limited to 'src/lib/entropy/entropy_src.h')
-rw-r--r-- | src/lib/entropy/entropy_src.h | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/src/lib/entropy/entropy_src.h b/src/lib/entropy/entropy_src.h new file mode 100644 index 000000000..552eca9de --- /dev/null +++ b/src/lib/entropy/entropy_src.h @@ -0,0 +1,141 @@ +/* +* EntropySource +* (C) 2008-2009 Jack Lloyd +* +* Distributed under the terms of the Botan license +*/ + +#ifndef BOTAN_ENTROPY_SOURCE_BASE_H__ +#define BOTAN_ENTROPY_SOURCE_BASE_H__ + +#include <botan/buf_comp.h> +#include <string> + +namespace Botan { + +/** +* Class used to accumulate the poll results of EntropySources +*/ +class BOTAN_DLL Entropy_Accumulator + { + public: + /** + * Initialize an Entropy_Accumulator + * @param goal is how many bits we would like to collect + */ + Entropy_Accumulator(size_t goal) : + entropy_goal(goal), collected_bits(0) {} + + virtual ~Entropy_Accumulator() {} + + /** + * Get a cached I/O buffer (purely for minimizing allocation + * overhead to polls) + * + * @param size requested size for the I/O buffer + * @return cached I/O buffer for repeated polls + */ + secure_vector<byte>& get_io_buffer(size_t size) + { io_buffer.resize(size); return io_buffer; } + + /** + * @return number of bits collected so far + */ + size_t bits_collected() const + { return static_cast<size_t>(collected_bits); } + + /** + * @return if our polling goal has been achieved + */ + bool polling_goal_achieved() const + { return (collected_bits >= entropy_goal); } + + /** + * @return how many bits we need to reach our polling goal + */ + size_t desired_remaining_bits() const + { + if(collected_bits >= entropy_goal) + return 0; + return static_cast<size_t>(entropy_goal - collected_bits); + } + + /** + * Add entropy to the accumulator + * @param bytes the input bytes + * @param length specifies how many bytes the input is + * @param entropy_bits_per_byte is a best guess at how much + * entropy per byte is in this input + */ + void add(const void* bytes, size_t length, double entropy_bits_per_byte) + { + add_bytes(reinterpret_cast<const byte*>(bytes), length); + collected_bits += entropy_bits_per_byte * length; + } + + /** + * Add entropy to the accumulator + * @param v is some value + * @param entropy_bits_per_byte is a best guess at how much + * entropy per byte is in this input + */ + template<typename T> + void add(const T& v, double entropy_bits_per_byte) + { + add(&v, sizeof(T), entropy_bits_per_byte); + } + private: + virtual void add_bytes(const byte bytes[], size_t length) = 0; + + secure_vector<byte> io_buffer; + size_t entropy_goal; + double collected_bits; + }; + +/** +* Entropy accumulator that puts the input into a Buffered_Computation +*/ +class BOTAN_DLL Entropy_Accumulator_BufferedComputation : + public Entropy_Accumulator + { + public: + /** + * @param sink the hash or MAC we are feeding the poll data into + * @param goal is how many bits we want to collect in this poll + */ + Entropy_Accumulator_BufferedComputation(Buffered_Computation& sink, + size_t goal) : + Entropy_Accumulator(goal), entropy_sink(sink) {} + + private: + void add_bytes(const byte bytes[], size_t length) override + { + entropy_sink.update(bytes, length); + } + + Buffered_Computation& entropy_sink; + }; + +/** +* Abstract interface to a source of entropy +*/ +class BOTAN_DLL EntropySource + { + public: + /** + * @return name identifying this entropy source + */ + virtual std::string name() const = 0; + + /** + * Perform an entropy gathering poll + * @param accum is an accumulator object that will be given entropy + */ + virtual void poll(Entropy_Accumulator& accum) = 0; + + virtual ~EntropySource() {} + }; + +} + +#endif |